Telephone system



March 24, 1.942.

c. D. KQECHLING TELEPHONE SYSTEM 3 Sheets-Sheerl 1 Filed July, 1940 /N VE /V TOR c. 0, Kob-CHL /NG B V T TORNE V March 24, v1942., c. D.KOECHLING 2,277,441

TELEPHONE SYSTEM Filed July 5, 1940 3 sheetsheet 2 Q I N n v I n, /N VENTOR c. .0. KOECHL/NG March 24, 1942.

y Filed July 5, 1940 C. D. 'KOECHLING TELEPHONE SYSTEM ATTE/WANTS serF/as I A7' LOCATION C 3 Sheets-Sheet 3 v A l, IL. Il

5s/I, To laz ncl/.frits ok NI/ENTOR C. D. KOECHL/NG BV ArrjORA/EyPatented Mar. 24, 1942 OFFICE TELEPHONE SYS TEM Application July 5,1940, Serial No. 344,039

7 Claims.

This invention relates to telephone systems and particularly toautomatic working, being especially directed to transferring meanswhereby connections extended to one point may be rerouted to anotherpoint.

The object of the invention is to provide facilities whereby flexibleoperation by a subscriber having a plurality of terminating stations indifferent localities may be had.

The prior art affords a number of disclosures of telephone systemswherein calls may be transferred from one called subscriber to anothercalled subscriber. Generally speaking such facilities are provided inspecial private branch exchange arrangements. The present invention,however, contemplates a plurality of private branch exchangeinstallations and the object is to transfer a vcall incoming to one suchprivate branch exchange operator to another and particularly where thedifferent private branch exchange switchboards are in diierentlocalities. The present invention therefore differs from previouslyknown arrangements in several essential aspects.

In accordance with one feature of the invention the transferarrangements While still controlled by a called subscriber arenevertheless located at the distant end of the line. Specifically, thetransfer is made at the central office end of a trunk rather thanlocally in the private branch exchange circuits.

In accordance with another feature the transfer is more in the nature ofa rerouting since the new connection is not directively extended to aparticular called subscribers line but rather to another group of linesleading in the desired direction.

A further feature of the invention is a simple key controlled means forinitiating the transfer or rerouting operation at the distant end of thetrunk line. In the specific embodiment of the invention herein employeda differential relay at the central office end of a trunk is made torespond to a manual key controlled operation at the private branchexchange end of the trunk.

In accordance with another feature each of a group of central cnicelines terminating in a distributing means for allotting incoming callsto individualattendants of a group has in it a transfer means operatedby a common key at each attendants position to affect transfer means atthe central office end of the line for there transferring or reroutingthe call over one of another group of lines extending to a differentlocation. Where a subscriber has premises at two widely separatedlocations and where cable conductors are at a premium the, presentinvention becomes a means ytoward economy especially since additionaltie line facilities need not be provided for transferring calls directedto one location which are to be handled at another location.

In accordance with a further feature of the invention such transferredconnections may be used for conference purposes since the originalconnection to the subscribers premises to the irst location is notdestroyed after being transferred or rerouted though it may beabandoned.

Other features will be set forth in detail in the following description.

The drawings consist of three sheets.

Fig. l is a schematic diagram showing the general plan of operation; and

Figs. 2 and 3 with Fig. 3 placed to the right of Fig. 2 provide acircuit diagram for explaining the present invention.

In Fig. l the diagram is divided into three portions by a dot-and-dashline. The portion to the left of the vertical ldot-and-dash linerepresents central office circuits. The two portions to the right of thedot-and-dash line represent the premises of a subscriber, the upperportion representing premises at one location and the lower portionrepresenting premises at another location. A subscriber A wishing tocall subscriber B and selecting the telephone number of subscriber Bleading to his premises at location C will set up a connection to a linel leading to subscriber B at location C. This line l passes through atransfer circuit 2 over line 3 to an incoming circuit arrangement ilwhich may be attended by an attendant having a circuit 5. The attendantnding that the subscriber A in reality wished to talk to an employee ofsubscriber B at location D thereupon performs a manual operation withinthe attendant's telephone circuit 5 which ycauses a relay operation inthe incoming trunk circuit 4 and which in turn causes an operation inthe transfer circuit 2; thereupon a finder switch 6 will operate andextend the line over an idle trunk circuit 'I leading to the premises ofsubscriber B at location D where the call will be answered by anattendant having supervision over the central oice trunk circuit 8. In asimilar manner a subscriber E may set up a connection to the line 9leading to the premises of subscriber B at location D. This line passesthrough a transfer circuit l similar to the transfer circuit 2, thenceover a central oice line Il to a trunk termination circuit I2 on thepremises of subscriber B at location D, and thence to a termination I3in a private branch exchange switchboard. The attendant here, findingthat the subscriber E actually wished to talk to an employee ofsubscriber B at location C, performs the same sort of manual operationas the attendant at location C whereupon a dierential relay in thetransfer circuit I causes the trunk finder circuit I4 to operate andextend the connection over an idle trunk I5 leading to the premises ofsubscriber B at location C. The line I6 terminates at that point in anincoming trunk circuit Il which may be attended by the attendant havingcharge of the attendants telephone circuit 5.

The facilities provided by the trunk nder circuits such as I4 may beutilized by employees of subscriber B for setting up connections tofellow employees at the other location; thus a subscriber F may set up aconnection through the station line circuit I8 to a trunk circuit I9which will cause the operation of the trunk circuit I4 in the samemanner as the transfer circuit I0 causes this operation, whereupon thesubscriber F, employee of subscriber B, may be connected to a fellowemployee at the location C.

The essential parts of the circuit are shown in Figs. 2 and 3. For amore complete disclosure of the circuits of this nature, reference maybe had to Patent 1,841,093 to Dahl, January 12|, z

1932. The circuits shown in Figs. 2 and 3 are modifications of thecircuit shown in great detail in the above-noted Dahl patent. Asubscriber at station may establish a connection, by way of example,through automatic switches 2I and 22 to a line 23 leading to a linetermination circuit shown to the right of the dot-anddash line in Fig.3. This line termination circuit in turn leads to an automatic switchhere designated by wipers 24, and 26 leading to an attendants telephoneset. The manner in which such a call distributing switch is operated iswell known so that here only the parts of the circuit external to thepresent invention are indicated. It will be noted that between switches2I and 22 a source of talking battery is furnished to the line in theform of a ground connection to the tip conductor 2l and a batteryconnection to the ring conductor 28. Battery and ground then cause acurrent flow in a loop circuit so that this flow of current is equal andopposite in the two conductors. Since these two conductors lead throughwindings of relay 29, this current flow will not cause relay 29 tooperate.

Thus relay 29 is not operated during the normal use of the line fromsubscriber 2U to the attendant having charge of the attendants telephoneset 30.

If the attendant nds that the call should have gone to some otheremployee at another location, she Will operate transfer key 3I. This keywill set up a potentiometer connection including the resistances 32 and33 and a middle point leading through wiper 26 and thence through thewinding of transfer relay 34 to ground on the back contact and lowerarmature of relay 35. If relay 35 is non-operated, as it would be duringthe normal use of the line since at that time relay 36 would beoperated, then relay 34 will respond. Since the supervisory relay 31will be operated while the attendants telephone set 30 is oonnected tothe line, the operation of relay 34 will place a ground on the ringconductor of the line and through the resistance 38 also on the tipconductor. This will result in a great decrease of current through theleft-hand winding of relay 29 and a great increase in the currentthrough the right-hand winding of relay 29. Relay 29 thereupon operatesand causes the consequent operation of start relay 39.

Relay 39 through its outer right-hand armature and front contact placesa ground on terminal 40 individual to the line 23. Through its innerright-hand armature and front contact relay 39 short-circuits theleft-hand winding of relay 29 so that relay :29 will remain operatedthereafter even though the attendant at the distant end releases thetransfer key 3i. Through its inner left-hand armature and front contactstart relay 39 establishes a circuit from ground to the right-handarmature of back contact of cut-o relay 4| through the inner left-handarmature and front contact of relay 39, winding of relay 42 to battery.Relay 42 places a ground on group contact 43 of the finder switch heredesignated by its group contact wiper 44 and the four upper wipers ofwhich No. 45 is one. Relay 42 also extends a ground from its left-handarmature and front contact to the winding of relay 46 which, becomingoperated, closes a circuit from ground, inner left-hand armature andfront contact of relay 46, armature and back contact of vertical magnet4'I, back contact and upper armature of rotary magnet 43, left-handwinding of relay 49, back contact and outermost left-hand armature ofrelay 59 to battery. Relay 49, becoming operated, establishes a circuitfrom ground, the inner left-hand armature and front contact of relay 45,the armature and front contact of relay 49, the inner left-hand armatureand back contact of relay 5l, Winding of vertical magnet 4l, to batteryat the back contact and outer left-hand armature of relay 5U. Verticalmagnet 4T moves the brushes of this switch on step in a verticaldirection and by opening the circuit of relay 49 thereby breaks its owncircuit. Thus the vertical magnet will automatically step until it isstopped by brush 44 reaching terminal 43. At this time a circuit will beestablished from ground, righthand armature and front contact of relay42, group terminals 43, brush 44, left-hand winding of relay 5I, backcontact and upper armature of rotary magnet 48 through the left-handwinding of relay 49 to battery on the back contact and outer left-handarmature of relay 50. As this circuit is completed while the verticalmagnet 4'I has opened the circuit through its armature and back contact,relay 49 will not release at this time and thus vertical magnet 4l willnot be allowed to close this circuit. Relay 5I responds and closesthrough a substitute circuit for holding the vertical magnet 4'I as wellas the relay 5| energized through its right-hand winding, front contactand right-hand armature.

A circuit for the rotary magnet 48 may now be traced from battery towinding of rotary magnet 48, front contact and inner left-hand armatureof relay 5I, front Contact and armature of relay 49, front contact andinner left-hand armature of relay 46 to battery. Magnet 48 operates tomove the brushes represented by 45 in a rotary direction and by movingits armatures breaks the circuit of relay 49. Relay 49 becomesdeenergized and thus opens the circuit for the rotary magnet 43. By thismeans the rotary magnet 48 automatically steps the brushes 45 arounduntil the grounded terminal 40 is reached. At this time ground will beextended to the winding of relay 52. Relay 52 operates. At the same timea connection is set up from battery, the

winding of cut-01T relay 4I through the outer left-hand armature andfront contact of relay 39, the terminal 53 and its associated brush,leithand winding of relay 54, back contact and middle left-hand armatureof relay 50, right-hand Winding of relay 49 to ground on the frontcontact and outer left-hand armature of relay 46. The cut-off relay 4lwill operate in this circuit and lock through its left-hand armature andfront contact to the condition found on terminal 53. Relay 49 willremain operated to prevent further stepping of rotary magnet 48 so thatthe brushes now having found the proper line will remain stationary.Relay 4l removes ground from the winding of relay 42 and this relayallows relay 46 to become deenergized. Relay 54 is also operated andserves to cut through the line to the contacts of relay 55. Relay 54locks in a circuit from battery through its right-hand winding, frontcontact and inner right-hand armature, through the lower armature andfront contact of rotary stepping magnet 48 to ground on the frontcontact of relay 46, which is slow to release and which holds grounduntil relay 50 becomes operated. Upon the operation of relay 54, groundis extended from the lower contacts of the vertical off-normal set ofcontacts 56 through the front contact and outer righthand armature ofrelay 543, left-hand winding of relay 50 to battery. Relay 50 nowbecomes operated and removes the battery connection for the operation ofthe vertical and rotary magnets, but establishes a connection for theholding of relay 54 which may be traced from battery to right-handwinding of relay 54, front contact and inner right-hand armaturethereof, inner lefthand armature and front contact of relay 55 to groundat the front contact of outer right-hand armature of relay 52. Relay 5Ibecomes deenergized.

When relay 52 is operated, ringing current from a source connected toconductor 5l is connected through the outer left-hand armature and frontcontact of relay 52 through the left-hand winding of tripping relay 55,back contact and inner left-hand armature of relay 55, front contact andleft-hand armature of relay 52 to line conductor 58, and ground isconnected from conductor 59 through the inner right-hand armature andfront contact of relay 52, the contacts 60 and 6I controlled by theright-hand armature o-f relay 55 through the front contact and innerright-hand armature of relay 52 to line conductor 62. When thesubscriber at the end of the line comprising conductors 58 and 62responds, the current ilowing through the left-hand winding of relay 55may be increased and this relay will become operated, its right-handwinding thereupon being included in a circuit to ground at the outerright-hand armature of relay 52. The operation of relay 55 also cutsthrough the line from the line 23 to the line comprising conductors 58and 62 and cuts oi all connections through the source of ringing currenton conductors 51 and 59.

When the connection is to be released through well-known means, thebattery and ground connection to conductors 2'! and 28 will be released,resulting in the deenergization of relay 25. This allows relay 39 tobecome deenergized which removing ground from the terminal 4) will allowrelay 52 to release. This relay removes the ground connection from theconductor connected to its front contact associated with its outerright-hand armature and this breaks the holding circuit for relay 54.This relay in deenergizf ing establishes a circuit for the releasemagnet 5.3 from battery, the winding of release magnet 63, the upperpair of contacts of the vertical offnorrnal contacts 5.5, outerleft-hand armature and back contact of relay 5|, outer right-handarmature and back contact of relay 54, righthand armature and backcontact of relay 45 through the lower set of vertical off-normalcontacts 56 to ground. Release magnet 63 causes the switch 45 to returnto normal.

It should be noted that the connection from subscribers station 20 thusset -up to the attend.- ant having charge of the attendants telephone.Set 30 and thus transferred to the line conductors 58 and 52 leading tothe same subscribers premises at a different location, may be made thesubject of a conference connection, since the original connection to theattendants telephone set 35 is not destroyed when the connection to theline wires 58 and .62 is established. By the same token, the connectionin the new direction may be used and the attendant at the right of Fig.3 may abandon the connection without disturbing it.

What is claimed is:

1. In a telephone system, a central oiilce, a plurality of groups oflines extending from said central office to subscribers premises, eachsaid group extending to a subscribers premises at a diiferent location,means individual to each of said lines at said central oice responsiveto manual control at the said subscribers premises for automaticallyextending said line from said central office to an idle one of saidlines in a predetermined one of said groups of lines.

2. In a telephone system, a central oice, a group of lines extendingfrom said central office to a first subscribers premises, another groupof lines extending from said central oice to a second subscriberspremises, means at said central cnice individual to each of said linesof said first group responsive to control from said first subscriberspremises for causing said lines to be automatically extended to an idleone of said lines of said second group.

3. In a telephone system, a central office, a group of lines extendingfrom said central office to a rst subscribers premises, automatic linenders at said central office for extending each of said lines, a secondgroup of lines extending from said central office to a secondsubscribers premises, said second group of lines each terminating in oneof said line finders and means at said central office individual to eachof said lines of said rst group under manual control from said firstsubscribers premises for automatically causing the operation of saidline iinders.

4. In a telephone system, a central oice, a group of lines extendingfrom said central oice to a subscribers premises at a first location,another group of lines extending from said central oice to saidsubscribers premises at a second location, means individual to each ofsaid lines of said first group at said central oflice responsive tomeans individual to each of said lines of said first group at saidsubscribers premises at said first location for extending each of saidlines of said rst group to an idle one of said lines of said secondgroup extending to said subscribers oice to said subscribers premises ata second location, a differential relay in each of said lines of saidrst group at said `central oiiice unresponsive to normal use of saidlines, means individual to each of said lines of said rst group at saidsubscribers premises for operating said differential relays, a switchfor extending each of said lines of said first group to one of saidlines of said second group, said switches being under control of saiddifferential relays.

6. In a telephone system, a central oice, a group of lines extendingfrom said central oice to a subscribers premises at a first location,another group of lines extending from said central oflice to saidsubscribers premises at a second location, an attendants position atsaid first location accessible to said lines of said rst group, means ineach of said lines of said rst group at said rst location for placing adistinctive condition on said lines, means in said attendants positioncommon to said lines for operating said distinctive conditioning means,means in each of said lines of said rst group at said central ofliceresponsive to a said last-named means for extending said lines to one ofsaid lines of said second group.

7. In a telephone system, a central ofice, a group of lines extendingfrom said central oiice to a subscribers premises at a first location,another group of lines extending from said central oiiice to saidsubscribers premises at a second location, a plurality of attendantspositions at said rst location accessible to said lines of said rstgroup, a transfer relay in each of said lines of said rst group at saidfirst location, a transfer key in each of said attendants positions forcontrolling said transfer relays, a second transfer relay in each ofsaid lines of said irst group responsive to said rst transfer relays andmeans under control of said second transfer relays for transferring acall on one of said lines of said rst group to one of said lines of saidsecond group.

CHARLES D. KOECHLING.

